High voltage contactor

ABSTRACT

An improved high voltage contactor of the type having arc horns associated with the current-carrying contacts, the arc produced by the interruption of the circuit being supported by the arc horns and there-after being extinguished. The described contactor includes a movable closure mechanism comprising an arm or closure having a first and a second element, the second element being pivoted with respect to the first. A set of arc horns, each of which is associated with a contact tip, are disposed so that there is a gap between them when the contact tips are fully closed. In order to open the contact tips, initial rotation of the first element of the closure causes the second element thereof to tilt with respect to the first, forcing the arc horns into contact before the current-carrying contacts have separated. Further rotation causes the contacts to separate, the arc horns still abutting one another. Still further rotation causes the arc horns to separate, striking an arc therebetween. The arc is generated within an arc extinguishing housing having baffles which lengthen and cool the arc to facilitate its extinguishment.

United States Patent [191 McFarland June 10, 1975 HIGH VOLTAGE CONTACTORGeorge L. McFarland, Salem, Va.

[73] Assignee: General Electric Company, Salem,

[22] Filed: Dec. 19, 1973 [21] Appl. No.: 426,063

[75] Inventor:

[52] US. Cl. 200/146 R; 200/144 R [51] Int. Cl. H01h 33/12 [58] Field ofSearch 200/146 R, 144 R [56] References Cited UNITED STATES PATENTS2,031,516 2/1936 Tritlc ZOO/I46 R 2,318,086 5/1943 Lindstrom 200/l46 RPrimary Examiner-Robert S. Macon Attorney, Agent, or FirmW. C. Bernkoft;.l. H. Beusse [57] ABSTRACT An improved high voltage contactor of thetype having arc horns associated with the current-carrying contacts, theare produced by the interruption of the circuit being supported by thearc horns and thereafter being extinguished. The described contactorincludes a movable closure mechanism comprising an arm or closure havinga first and a second element, the second element being pivoted withrespect to the first. A set of arc horns, each of which is associatedwith a contact tip, are disposed so that there is a gap between themwhen the contact tips are fully closed.

In order to open the contact tips, initial rotation of the first elementof the closure causes the second element thereof to tilt with respect tothe first, forcing the arc horns into contact before thecurrent-carrying contacts have separated. Further rotation causes thecontacts to separate, the arc horns still abutting one another. Stillfurther rotation causes the arc horns to .separate, striking an arctherebetween. The are is generated within an arc extinguishing housinghaving baffles which lengthen and cool the arc to facilitate itsextinguishment.

1 Claim, 4 Drawing Figures PATENTED JUN l 0 I975 SHEET PATENTEDJUH 10 ms3. a 89,082 SHEET 2 FIG. 4

HIGH VOLTAGE CONTACTOR BACKGROUND OF THE INVENTION The present inventionrelates to circuit interrupting means and, more particularly, to circuitbreakers or contactors designed for use with high currents which causearcing to occur upon circuit interruption.

Despite the great variety of mechanisms which have been devised to makeand break electrical circuits, certain problems have inhered in thisactivity. One of the most severe problems occurs in the interruption ofan electrical circuit carrying high DC currents, for instance in theneighborhood of 1,000 amps or more. When such a circuit is broken bymechanical means, such as by physically separating current-carryingcontacts, an arc ordinarily forms between the contacts as they separatein order to maintain current flow. Various approaches to the quenchingof this are have been posed from time to time including complexmechanical movements, means for interposing insulating materials betweenthe current-carrying contacts, means for displacing the arc, and meansfor transferring the arc to other elements remote from thecurrent-carrying contacts which more readily withstand the detrimentaleffects of the arcing.

In one popular type of contactor arc supporting means, which are oftendescribed as arc horns, are associated with the contact tips andoriented so that after contacts open the arc struck therebetween istransferred to the arc horns. However, such a transfer of the are, nomatter how rapid, necessarily has some detrimental effects upon thesurface of the contact tips and upon their ability to interrupt currentflow. Moreover, it is sometimes necessary to provide auxiliary means forcausing the arc to travel from the contact tips to the arc horns. Suchmeans may take the form of a blowout coil, an electrical winding andassociated magnetic poles which create a strong magnetic field todeflect the arc and cause it to travel further out upon the the archorns. In some instances, the arc horns are stationary and divergent,with arc suppressing means such as baffles interposed between theirextremities. As

- the arc travels out upon the arc horns its length necessarilyincreases, and due to the baffles a tortuous path is presented all ofwhich serve to aid in cooling and extinguishing the are.

In some designs, the arc horns are formed to move apart, enlarging thelength of the arc and facilitating its extinguishment. In still otherinstances, auxiliary sets of contacts are provided to temporarily bypassthe main current-carrying contacts, the auxiliary contacts subsequentlyopening after the main contacts have opened and striking an arcthereacross. Although this activity is detrimental to the auxiliarycontacts, this result is tolerated since they are not relied upon tocarry load current. Such contacts, however, need frequent replacementbecause of the effects of arcing thereupon.

Arc horns which are associated with the contact tips and to which aretransferred an arc originating between the tips, may have a much longerlife than auxiliary contacts but the requirement that the arc be.initiated at or near the contact tips is extremely detrimental to thetips themselves. Moreover, after the arc has been struck betweenrelatively wide contact tipsit is difficult to thereafter displace thearc into a narrow quenching chute. It will therefore be understood thatit would be highly desirable to provide improved contactor means whichprovide for the supporting of an arc by are supporting elements, withoutthe necessity for initiating an arc between the current-carryingcontacts themselves.

It is therefore an-object of the present invention to provide improvedcircuit interrupting means in which an arc is initiated between archorns.

It is another object "of the present invention to provide means for thetransferring of flow of current to are supporting means before theopening of main currentcarrying contacts.

Still another object is to provide circuit interrupting means in whichan arc is initiated in a space which is substantially narrower than thewidth of currentcarrying contact tips.

SUMMARY OF THE INVENTION Briefly stated, in.accordance with one aspectof the invention, the foregoing aspects are achieved by providing acontactor with closure means which comprise two elements, one of thecurrent-carrying contact tips of the contactor being disposed upon thesecond of the elements. The first element is pivoted to rotate about apoint in order to actuate the contactor. A fulcrum is provided upon thefirst or the second element, and biasing means disposed adjacent thefulcrum. Upon complete actuation of the contactor, the contact tips areclosed with'the are supporting means separated by a predetermined gap.As the contactor is opened and the closure begins to rotate, the secondelement thereof pivots about the fulcrum and changes its orientationsuch that the arc supporting means are broughtinto contact with oneanother. Current then begins todecrease through the main contact tipsand increase to encourage the displacement of the are along the aresupporting means.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims particularly pointing out and distinctly claiming the subjectmatter which is regarded as the invention, it is believed that theinvention will be better understood from the following description ofthe preferred embodiment taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a simplified drawing of a high voltage contactor embodying thepresent invention, in a fully closed position;

FIG. 2 is the contactor of FIG. 1 showing operation of the elementsthereof preparatory to the breaking of a circuit; and

FIG. 3 shows a subsequent position of the elements of the contactorimmediately prior to the breaking of a circuit.

FIG. 4 is a partial horizontal cross-section of the contactor of thepresent invention showing the narrowed arc supporting means positionedwithin the narrow arc chute.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows, in simplifiedform, elements of a high voltage contactor constructed in accordancewith the present invention. A housing 2 is provided with narrow arcsuppressing area 3, ordinarily termed an arc chute. A plurality ofbaffles 4extend from opposite sides of the chute so as to be interleavedwith one another and thus create a tortuous path. A first bus 6 isprovided with means for attaching a conductor to connect the contactorto oneside of a circuit. Bus 6 is coupled to a first, stationary contacttip 8 and, by means of a winding 10 to a first are supporting means,here shown as are horn 12. Winding 10 comprises the winding of asocalled blowout coil formed around a magnetic core 14. Core 14 extendsthrough winding 10 and connects a pair of pole pieces 15 disposed oneither side of arc horn 12 for purposes to be explained hereinafter.

A second bus 16 is provided for connection of the contactor to the otherside of the circuit, and flexible lead 18 connects bus 16 to closuremeans comprising a first element 20 and a second element 22. The firstelement of the closure member is journaled upon a shaft 24 and pivotsthereon in order to effect operation of the contactor. The secondelement 22 of the closure carriesfa second, movable contact tip 23 whichabuts first,stationa'r y contact tip 8 to form the main current carryingpath of the contactor. The second element 22 also provided with an aresupporting element 26, here 'shown as comprising a suitably-formedextension of the member. In the preferred embodiment, the arc supportingmeans 12 and 26 are substantially narrower than contact tips 8 and 23and are located within the narrow arc chute 3.

The first and second elements of the closure means are coupled togetherby means of a fulcrum 28 and a biasing means, here shown as theassembled combination of a bolt 30 and a spring 32. A stop 33 isdisposed upon first element 20. It is assumed that suitable means willbe provided for actuating the closure member and for holding it in anopen or a closed position as shown in FIG. 1. Since much means arecommon knowledge in the art and form no part of the present inventionthey are not shown, in order to simplify the Figures.

In order to complete a circuit the closure member is forced upwardly bysome suitable means, such as a mechanical mechanism 4 or anelectromagneticallyactuated armature, until it reaches the positionshown. The stationary and movable contacts 8 and 23 are now held inclose abutment, and current flows therethrough. Arc horns 12 and 26however, although electrically connected to contact tips 8 and 23respectively, are separated by an air gap and therefore are notconsidered to be in the electrical circuit. Current now flows throughbus 6, stationary contact tip 8, movable contact tip 23, and exits fromsecond element 22 of the closure member by way of flexible cable 18 andbus 16.

Referring now to FIG. 2, in order to break the circuit the closure meansundergoes rotation in the clockwise sense. When first element 20 hasbeen rotated through a first angle 4) l the bias provided by spring 32forces the second element 22 to pivot in a counterclockwise directionabout the fulcrum 28. The tilting effect thus achieved changes theangular relationship between contact tips 8 and 23 but does not separatethem. Rather, second element 22 rocks upon the stationary contact tip 8until arc horn 26 is brought into contact with the opposing face of archorn 12.

It will now be seen that the series combination of blowout coil 10, arehorn l2 and are horn 26 form a circuit which is in parallel circuitrelationship with contact tips 8 and 23. At this point, current beginsto flow through winding 10 and the abutting arc horns.

FIG. 3 shows the inventive mechanism in a final stage of operation, justbefore separation of arc horns l2 and 26. Further rotation of the firstelement 20 of the closure means has proceeded through a second angle (1)2. So that the second element is about to encounter stop 33, and spring32 and fulcrum 28 have cooperated to tilt the second element 22 stillfurther with respect to first element 20.

Since a point of contact had previously been established between archorns' 12 and 26 the further angular displacement of second element 22with respect to first element 20 of the closure means effects aseparation of contacts 8 and 23. However, since a bypass circuitcomprising blowout coil 10 and are horns l2 and 26 has already beenestablished, upon opening of the contacts full current flows through thewinding and arc horns. The voltage now arising across the contact tips 8and 23 is insufficient to cause a significant arcing to occur. Further,the current now flowing through winding 10 induces magnetic flux in themagnetic core means 14. As stated above core means 14 includes polepieces 15 disposed upon either side of the arc horns, in

the general vicinity of the point at which the arc horns' contact oneanother. The direction of the flux traversing the arc horns may beconsidered to be normal to the plane of the Figures.

It will now be apparent that upon further clockwise movement of firstelement 20, are horns 12 and 26 will separate once second element 22comes to rest across fulcrum 28 and stop 33. Having achieved thisposition, first and second elements 20 and 22 will rotate as a unit in aclockwise fashion, rapidly enlarging the gap between arc horns 12 and26. As the gap is enlarged the length of the arc supported between thearc horns also increases. Due to the magnetic field supported by coremeans 14 and according to the wellknown right hand rule, the arc currentand the magnetic field will interact. The arc will then be deflected tothe right, toward the ends of the arc horns in order to increase stillfurther the length of the arc path. In addition, as it approaches theends of the arc horns the arc encounters the interleaved baffles 4 ofarc chute 3. The cooling effect of the baffles on the arc, and thetortuous path presented thereby, cooperate to force extinguishment ofthe arc in a manner well known to those skilled in the art.

In prior art devices in which the arc is struck between the contact tipsit is necessary to thereafter force the are into a relatively narrow arcchute to quench and extinguish it. With the disclosed apparatus,however, the arc horns may be substantially narrower than the contacttips and advantageously extend within the confines of a narrow arc chute3. The arc is then initiated within the arc chute, obviating thedifficulties inherent in attempting to compress a large arc into arelatively narrow opening.

In closing the contactor the sequence of events described above arerepeated, in reverse order. Initial electrical contact is made betweenarc horns 12 and 26; however, since there is no arc struck the magneticfield created by blowout coil 10, magnetic core 14 and pole pieces 15has little effect upon the conduction of current between the arc horns.Further rotation of first element effects a pivoting of second element22 between the points of contact of the arc horns and ful crum 28, untilthe main current carrying contact tips touch. A second conductive pathis then constituted in parallel with the original path which includedthe arc horns and blowout coil 10, and current begins to flow throughthe abutting contact tips. Finally, rotation of first element 20 to itsfinal position effects a further pivoting of second element 22 aboutfulcrum 28 and the abutting contact tips so as to cause the arc horns l2and 26 to separate. Since conduction has already been establishedbetween the contacts, no arc is drawn between the arc horns uponseparation. The circuit breaker is now fully closed, and full loadcurrent will flow through the contacts until the circuit breaker isreopened.

As will be evident from the foregoing description, certain aspects ofthe invention are not limited to the particular details of the examplesillustrated, and it is therefore contemplated that other modificationsor applications will occur to those as skilled in the art. It isaccordingly intended that the appended claims shall cover all suchmodifications and applications as do not depart from the true spirit andscope of the invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A contactor having an arc supporting capaability and comprising:

a housing including arc suppression means comprising an arc chute;

a stationary contact tip for carrying current when saidcontactor isclosed;

first arc supporting means electrically connected to said stationarycontact tip and disposed within said arc chute for carrying currentduring the opening and closing of said contactor;

closure means pivotally mounted within said housing;

a second contact tip disposed upon said closure means for makingelectrical contact with said first contact tip to effect closing of saidcontactor;

second arc supporting means fixedly connected to said second contact tipand disposed so as to be separated a predetermined distance from saidfirst are supporting means after closing of said circuit breaker and tocontact said first are supporting means upon pivoting of said closuremeans; and

said arc chute and said first and second arc'supporting means having awidth substantially less than the width of said contact tips, saidsecond arc supporting means extending into said are chute wherein arcingbetween said first and second are supporting means is initiated withinsaid arc chute.

1. A contactor having an arc supporting capaability and comprising: ahousing including arc suppression means comprising an arc chute; astationary contact tip for carrying current when said contactor isclosed; first arc supporting means electrically connected to saidstationary contact tip and disposed within said arc chute for carryingcurrent during the opening and closing of said contactor; closure meanspivotally mounted within said housing; a second contact tip disposedupon said closure means for making electrical contact with said firstcontact tip to effect closing of said contactor; second arc supportingmeans fixedly connected to said second contact tip and disposed so as tobe separated a predetermined distance from said first arc supportingmeans after closing of said circuit breaker and to contact said firstarc supporting means upon pivoting of said closure means; and said arcchute and said first and second arc supporting means having a widthsubstantially less than the width of said contact tips, said second arcsupporting means extending into said arc chute wherein arcing betweensaid first and second arc supporting means is initiated within said arcchute.